The existing and commonly used clinical thermometer can roughly be divided into two types, which is contact-type and non-contact-type, wherein the contact-type clinical thermometer is mainly two types as mercury clinical thermometers and electronic clinical thermometer. The electronic clinical thermometer does not use metal mercury, and the afraid for the dangerous of the overflow of the break of the clinical thermometer is unnecessary, meanwhile the reading is straightforward, and easy to operate, therefore it is more and more applied to the hospital and household.
The electronic clinical thermometer usually needs to draw support from the probe tip or probe to contact with the body for the measurement, and the error of the measurement is big, and the time for the measurement is long. In order to reduce the error, accelerate measuring the speed, usually we will adopt the way by which to pre-heat the probe tip or the probe, so that it will speed up the temperature of the probe tip or the probe to close with human body temperature, and then carry on the measure. However, to realize pre-heating of the probe tip or probe, we need the host of electronic thermometer has a validity way to check the motion of the probe tip and the probe, to know when to initiate the pre-heating process, and when to reset.
The American patent with a patent number of U.S. Pat. No. 7,021,824 discloses a switch device for a thermometer, which comprises a base installed on a circuit board, a probe, a probe bracket, a photonic transmitter and a photodetector. The switch device can detect the probe controlling action by using a powder supply, and cannot work without a circuit board. The switch device has the defects of complicated structure and high manufacturing cost.